- Mix 17.25 grams of agar with 750 mL of water to create agar plates
- Create 20 agar plates
- Create nutrient broth to allow bacteria to grow, by mixing 100 mL of water with .8 grams of bacteria broth
- Obtain E. Coli, and place in bacteria broth
- Allow broth to sit for at least 48 hours to allow E. Coli to grow
- Separate broth into two beakers, one for iodine testing, and one for control
- Apply .01 grams of iodine to bacteria broth
- Create dilutions necessary for experiment using a 1:10 ratio for the first plate, a 1;100 ratio for the second and so on, up to five plates for both the iodine and controlled solutions
- Place .3 mL of bacteria solution and dilutions on each plate
- Allow plates to sit in incubator for at least 24 hours
- Count colonies of bacteria in the 4th plate for each solution (1:1000000 dilution)
- Using Number of CFU/mL equation, determine amount of bacteria colonies in both iodine and controlled solutions
- Obtain Lugol's solution (5% iodine)
- Create 100 mL dilutions using .015 mL, 0.030 mL, 0.045 mL, 0.15 mL, and 100% Lugol's solution
- Test the heart rate of daphnia in a controlled solution containing no iodine
- Place daphnia in each dilution and record effects and heart rate change
Apparatus and Chemicals needed
250 ml Erlenmeyer Flask 20 agar plates Bacterial broth E. coli sample 17 g agar Iodine tablets Bunsen burner Sterilized pipet and spreader 100 mL beakers Petri Dishes Live Daphnia Lugol's solution
Safety information
-goggles
- gloves
- careful with bunsen burner
- careful with bacteria
- wash hands
- be careful handling live daphnia
- careful with lugol's solution
Abstract:
Water Purification. Peter Wood and Karl Hommeyer. Unhealthy drinking water is a prominent issue leading to millions of deaths every year. The use of iodine of tablets is applied to bacteria filled water, testing how effective this method is when purifying water. E Coli is grown in a nutrient broth and then applied to agar plates. The bacteria colonies are then counted to judge whether or not the iodine is truly effective. Iodine tested plates and plain bacteria plates are grown to compare the effects of the purification method. After counting the bacteria colonies, it is concluded that the iodine tablets are in fact effective when purifying water. The iodine tested plates had a significantly lower amount of E Coli than the amount in the pure bacteria plates. Although this is true, the tablets do not completely kill the all of the bacteria, leaving room for further research in purifying methods. It could be very effective to combine other methods of purification with the use of iodine tablets, such as boiling or the use of bleach. After testing the tablets on the bacterial plates, dilutions of Lugol's solution are prepared and used to test the effects of iodine on live daphnia. The recommended amount of Lugol's solution for 1 liter is shown to be healthy for the daphnia, but exceeding too far over this amount shows a decrease in the heart rate of the daphnia. The conclusions reached in this lab apply to the real world by providing an easy way to purify unhealthy drinking water on the go. Many campers use iodine tablets to purify their water so it becomes healthy to drink. Unhealthy drinking water remains a very big issue every year, causing research in purification methods to become much more important. The recommended amount of Lugol's solution for 1 liter of water is shown to not be harmful for the daphnia, but when this amount is significantly raised, the solution becomes harmful, illustrating the effects of iodine on the daphnia. The relationship of iodine tolerance for daphnia compared to iodine tolerance for humans would be important to research in the future, as would discovering methods of counting the heart beats of the daphnia more effectively.
Keywords: Water, Purification, Iodine, E Coli, Bacteria, Daphnia, Lugol's
http://www.cdc.gov/hicpac/Disinfection_Sterilization/8_0Iodophors.html
- Create 20 agar plates
- Create nutrient broth to allow bacteria to grow, by mixing 100 mL of water with .8 grams of bacteria broth
- Obtain E. Coli, and place in bacteria broth
- Allow broth to sit for at least 48 hours to allow E. Coli to grow
- Separate broth into two beakers, one for iodine testing, and one for control
- Apply .01 grams of iodine to bacteria broth
- Create dilutions necessary for experiment using a 1:10 ratio for the first plate, a 1;100 ratio for the second and so on, up to five plates for both the iodine and controlled solutions
- Place .3 mL of bacteria solution and dilutions on each plate
- Allow plates to sit in incubator for at least 24 hours
- Count colonies of bacteria in the 4th plate for each solution (1:1000000 dilution)
- Using Number of CFU/mL equation, determine amount of bacteria colonies in both iodine and controlled solutions
- Obtain Lugol's solution (5% iodine)
- Create 100 mL dilutions using .015 mL, 0.030 mL, 0.045 mL, 0.15 mL, and 100% Lugol's solution
- Test the heart rate of daphnia in a controlled solution containing no iodine
- Place daphnia in each dilution and record effects and heart rate change
20 agar plates
Bacterial broth
E. coli sample
17 g agar
Iodine tablets
Bunsen burner
Sterilized pipet and spreader
100 mL beakers
Petri Dishes
Live Daphnia
Lugol's solution
- gloves
- careful with bunsen burner
- careful with bacteria
- wash hands
- be careful handling live daphnia
- careful with lugol's solution
Abstract:
Water Purification. Peter Wood and Karl Hommeyer. Unhealthy drinking water is a prominent issue leading to millions of deaths every year. The use of iodine of tablets is applied to bacteria filled water, testing how effective this method is when purifying water. E Coli is grown in a nutrient broth and then applied to agar plates. The bacteria colonies are then counted to judge whether or not the iodine is truly effective. Iodine tested plates and plain bacteria plates are grown to compare the effects of the purification method. After counting the bacteria colonies, it is concluded that the iodine tablets are in fact effective when purifying water. The iodine tested plates had a significantly lower amount of E Coli than the amount in the pure bacteria plates. Although this is true, the tablets do not completely kill the all of the bacteria, leaving room for further research in purifying methods. It could be very effective to combine other methods of purification with the use of iodine tablets, such as boiling or the use of bleach. After testing the tablets on the bacterial plates, dilutions of Lugol's solution are prepared and used to test the effects of iodine on live daphnia. The recommended amount of Lugol's solution for 1 liter is shown to be healthy for the daphnia, but exceeding too far over this amount shows a decrease in the heart rate of the daphnia. The conclusions reached in this lab apply to the real world by providing an easy way to purify unhealthy drinking water on the go. Many campers use iodine tablets to purify their water so it becomes healthy to drink. Unhealthy drinking water remains a very big issue every year, causing research in purification methods to become much more important. The recommended amount of Lugol's solution for 1 liter of water is shown to not be harmful for the daphnia, but when this amount is significantly raised, the solution becomes harmful, illustrating the effects of iodine on the daphnia. The relationship of iodine tolerance for daphnia compared to iodine tolerance for humans would be important to research in the future, as would discovering methods of counting the heart beats of the daphnia more effectively.
Keywords: Water, Purification, Iodine, E Coli, Bacteria, Daphnia, Lugol's